Tag Necklace

I recently bought a necklace and a chain On / Off is similar this type of necklace: http://upload.wikimedia.org/wikipedia/commons/1/1a/Gunfighter-6_Dog_Tag.jpg Therefore, I will have a very difficult time trying to make the back of this necklace. All advice and suggestions, Web articles, videos, etc. that would help me? Thank you very much to advance.

Some ideas: 1. Do it at the front and drag it around the neck, 2. Ask someone to do it for you and 3. Put it in another string that is easier Up: D x